The project is related to the hormonal regulation of lipid mobilization and of adipocyte metabolism in rats and hamster. We are particularly interested in the four areas listed: 1. The regulation of adenylate cyclase and of lipolysis by adenosine. 2. The regulation of signal transduction between catecholamine-receptor complexes and adenylate cyclase by thyroid hormones with particular emphasis on the guanine nucleotide binding proteins. 3. The mechanism by growth hormone regulates lipolysis in adipocytes. 4. The role of phospatidylinositol turnover in the regulation of intracellular calcium. Additionaly we are interested in testing the hypothesis that alpha-1 effects of catecholamines involve increased phosphatidylinositol turnover and elevation of cytosol calcium while alpha-2 effects are independent of calcium but are secondary to inhibition of adenylate cyclase.